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  Disk device, and position determination method for pickup headUSPTO Application #: 20080025166Title: Disk device, and position determination method for pickup head Abstract: This disk device includes a pickup head (PUH), a PUH shift control unit, and an inner circumference position detection unit. The PUH reads out data upon a disk. The inner circumference position detection unit detects whether or not the PUH has shifted to the inner circumferential edge of the disk. And, after having stopped the PUH in the neighborhood of a position at which the detection state of the inner circumference position detection unit changes over, the PUH shift control unit determines a shift time period T5 for the PUH when a predetermined operation has been performed. And, by supplying power during the time period T7, the PUH is stopped at a predetermined position. (end of abstract) Agent: Pillsbury Winthrop Shaw Pittman, LLP - Mclean, VA, US Inventor: Atsushi HIGASHIDE USPTO Applicaton #: 20080025166 - Class: 369 4428 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080025166. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE [0001]This Nonprovisional application claims priority under 35 U.S.C. .sctn.119(a) on Patent Application No. 2006-208685 filed in Japan on Jul. 31, 2006, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002]Generally, a read in region is located at the innermost circumferential portion of a DVD (for example, of a DVD-RW), and in this region there is recorded a TOC (Table Of Contents), in which the running time period and the start position of each item are recorded. When replaying the DVD, in order to read out this TOC, a so-called "re-zero" or initialization operation is performed, in which the position of a pickup head ("PUH") is set to (i.e. is determined as being) this read in region, which is at a position 24.3 mm.about.25.8 mm from the inner circumferential edge of the DVD, and is stopped there. [0003]However, more precisely, since sometimes there may be some deflection in the disk, the position to which the PUH is set and stopped in this re-zero operation is a predetermined position which is determined in the disk device in advance, "corresponding" to the read in region if, hypothetically, a disk were to be loaded in which the deflection is zero. In other words, the target position for performing the re-zero operation is determined as being, not by any means a position upon the disk, but rather with reference to a predetermined absolute position with respect to the disk device main body. In this specification it will be supposed that, when the technical terms "re-zero operation" and "position determination to within the read in region" are used, they are intended to convey this meaning. [0004]A disk replay device which performs such position determination to within the read in region is disclosed in Japanese Laid-Open Patent Publication 2005-332525. In this patent document, the concept is described of, when a predetermined supply time period has elapsed during position determination of the PUH to the read region, supplying a re-zero braking pulse having a voltage value of 2 V.about.3 V to the thread motor. According to this method, it is possible to positionally determine the PUH to within the read in region, which is the target, in an accurate manner, irrespective of any variation in the minimum start voltage of the thread motor. [0005]And, in Japanese Laid-Open Patent Publication Heisei 5-217182, there is disclosed a recording medium drive device which positionally determines the PUH to a position which corresponds to the read in region. In this patent document, a structure is disclosed in which the thread motor is driven and, by the PUH contacting against a switch which is provided at the inner circumferential edge and decelerating when this switch is turned ON, the PUH contacts against an end stop portion and the PUH is stopped. It is stated that, according to this structure, it is possible to perform position determination to the read in region in an accurate manner. [0006]However, with the device described in Japanese Laid-Open Patent Publication 2005-332525, since the re-zero braking pulse voltage is supplied when performing position determination to within the read in region, it is necessary to perform adjustment by experiment, in order not to shift the PUH in the opposite direction. Furthermore, with this device described in Japanese Laid-Open Patent Publication 2005-332525, even though consideration is given to variation of the minimum start voltage of the feed motor, there is no concept of evaluating what may be the extent of the state of variation of this minimum start voltage in each individual case, so that there has been the problem that it cannot cope with long term change and the like. As a result, for example, the user has been subjected to various causes of apprehension, such as for example that, no matter how many times the re-zero operation may be performed, after loading a DVD he will not be able to play it. [0007]And, with the method described in Japanese Laid-Open Patent Publication Heisei 5-217182, when reading out the read in region, since each time the PUH or the like contacts against the stop plate and is positionally determined by being stopped, accordingly the PUH or the like experiences a shock load each time even though it is decelerated, so there has been a fear that it may easily undergo long term change or damage. [0008]The present invention has been conceived in consideration of the problems described above, and its object is, in the re-zero operation of a disk device, to evaluate the ease of performing shifting of the PUH in each individual case, and to perform position determination to within the read in region in a more accurate manner based upon this evaluation. Furthermore, the present invention also takes as its object, if the re-zero operation has failed, to evaluate the ease of performing shifting of the PUH in each individual case, while performing a retry of the re-zero operation (hereinafter termed a "short re-zero operation"), and to perform position determination to within the read in region in a more accurate manner based upon this evaluation. SUMMARY OF THE INVENTION [0009]The disk device of the present invention includes a pickup head, a pickup head shift control unit, and an inner circumference position detection unit. [0010]The pickup head reads out data upon a disk. [0011]The pickup head shift control unit supplies power to shift the pickup head along the radial direction of the disk. [0012]The inner circumference position detection unit detects whether or not the pickup head has shifted to the inner circumferential edge of the disk [0013]And the pickup head shift control unit executes the following position determination operations in sequence: [0014](ST1): supplying power so that the pickup head shifts to the neighborhood of a position at which the detection/non-detection of the inner circumference position detection unit changes over, and stops; [0015](ST2): after the step ST1, supplying power so that the pickup head shifts in the direction towards the position at which the detection/non-detection by the inner circumference position detection unit changes over, and continuing to supply power over a time period T4 which is determined in advance to be sufficient for the detection/non-detection to change over; [0016](ST3): directly after the step ST2, starting supply of power to shift the pickup head in the opposite direction to the shift direction in the step ST2, and, when the detection/non-detection by the inner circumference position detection unit changes over, along with stopping the supply of power, also measuring the time period T5 from when this step ST3 started to when the detection/non-detection changed over; and [0017](ST4): after the step ST3, starting supply of power to shift the pickup head in the direction of the disk outer circumference, and, after a time period T7 which is determined based upon the time period T5 has elapsed, stopping this supply of power. BRIEF DESCRIPTION OF THE DRAWINGS [0018]FIG. 1 is a block diagram showing the structure of the main portion of an optical disk device which is an embodiment of the present invention; [0019]FIG. 2 is a figure showing a control procedure for a re-zero operation which is performed by a control unit of this optical disk device which is an embodiment of the present invention; and [0020]FIG. 3 is a figure showing a control procedure for a short re-zero operation which is performed by the control unit of this optical disk device which is an embodiment of the present invention, when a re-zero operation which it has already performed has failed. Continue reading... Full patent description for Disk device, and position determination method for pickup head Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Disk device, and position determination method for pickup head patent application. Patent Applications in related categories: 20080205212 - Optical head apparatus, information recording/reproducing apparatus including the optical head apparatus, and information recording/reproducing method - According to one embodiment, an optical head device provides a signal processing circuit which sets a control amount to move an objective lens so that a distance between the objective lens and a given recording layer of the an optical disc coincides with a focal position, an optical path length ... ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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